Monday, 24 September 2012

Juvenile Sabine's Gull over the Thames at Rainham today - my 14th larid species on the patch.

OK, I know - these are possibly the worst photos ever taken of a Sabine's Gull in Britain. But I will publish anyway and be damned, because this was a much-wanted bird for my patch at Rainham Marshes, Greater London. In fact, as well as being my first Sabine's in the capital for 24 years, it was also my 195th species at Rainham, and no less than the 14th gull species I've recorded there. It was the pelagic prize we'd all hoped for on a day-long river watch yesterday during rain and strong easterlies, only to leave disappointed; then today, with continued blustery weather on the Thames, this bird was found by Kev Jarvis from the south shore and picked up by Andy Tweed, Dave Smith and Howard Vaughan from the visitor centre at Rainham RSPB. A cracking gull, and one of nine larid species I logged today (2 Caspians, 33 Yellow-leggeds and a first-winter Mediterranean being the other noteworthy gulls), along with 14 Common Scoter.

The bird must have been the best part of half a mile away when I photographed it, favouring the south side of the river.

Thursday, 20 September 2012

There is a small but noteworthy list of Nearctic shorebirds that, for one reason or another, appear in Britain far less frequently than their numbers, distribution and migratory habits might suggest. Semipalmated Plover is one such species that I've blogged about before; another is Short-billed Dowitcher. More numerous on the eastern seaboard of North America than Long-billed Dowitcher, Short-billed is paradoxically far rarer than that species in mainland Europe. Yet on the Azores, prior to this year there were 24 records of Short-billed and just 10 of Long-billed, with two further records of unidentified dowitchers. Compare that ratio to Britain, where by the end of 2011 there was one accepted Short-billed compared to 209 Long-billed. This may be partly accounted for by Long-billed's breeding distribution extending into Siberia, so that some of our birds arrive from the east as well as the west, but that isn't the whole story.

The bird was always rather distant but showed well at times on the west scrape.

Another factor must be identification. It is notoriously difficult to separate the two species, especially for British birders who inevitably have limited or no field experience. The one previous British record of Short-billed dates from autumn 1999, when it was seen in both north-east Scotland and Teesside: the second and third, found this month in Dorset and Scilly respectively, were both initially thought to be Long-billed Dowitchers until photographic evidence confirmed otherwise. How many others might have been wrongly assigned to the sibling species, especially in less distinctive non-breeding adult plumage? I think there is a mentality in Britain that dictates any dowitcher here is a Long-billed until proven otherwise - a view perhaps borne from a past review which discounted some older records of claimed Short-billeds, before the ID criteria were better established.

Spooked by a Black-headed Gull, the bird reveals useful feather detail on the upperwings.

The bird in these images is the Dorset individual, which I caught up with twice today in morning and afternoon visits to Lodmoor RSPB - a major 'grip-back' 13 years on from having missed the 1999 bird when it was on Teesside (I arrived the morning after it departed ...). Scope views of today's bird were good, but photographically it was always too distant for detailed portraits. These heavily cropped images still give a reasonable feel for Short-billed Dowitcher in juvenile plumage, with its distinctive internal markings on the tertials and greater coverts being the single most important distinction from juvenile Long-billed. Several interested members of the public stopped to ask what we were looking at, and left somewhat bemused at the fact that this bird could be described as a short-billed anything!

The obvious notching on the tertials is a giveaway for juvenile Short-billed.

Sunday, 16 September 2012

This elusive Baillon's Crake was found on 7 September but has been absent for long periods and has proved very difficult to see. A juvenile, it follows a summer in which an unprecedented nine singing males were located on territory in Britain - conceivably, it may therefore be British bred. The two previous London records of this vagrant both date from the late 19th century.

Saturday, 15 September 2012

Juvenile Caspian Gulls are a rare sight in Britain, but probably overlooked. They are nothing like as distinctive as first-winter birds but, with practice, can be picked out among gatherings of other young gulls. I filmed the juvenile gull in this clip on 6 September when it showed well at my regular study site; I think it is a decent candidate Caspian, as do several other gull-watchers with considerably more experience of the species than me (though there has also been one suggestion for Lesser Black-backed Gull). There were up to five Caspians present that day. Of interest in this bird are its structure and posture, the long, slender and parallel-sided bill, the juvenile scapulars, and the pattern of the coverts and tertials. A bird to learn from, for sure.

Friday, 14 September 2012

Rewind to this day 20 months ago: Britain's first Slaty-backed Gull, at Rainham landfill, Greater London.

Exactly one year and eight months ago to the day, I was out on my local patch, sitting on a huge pile of earth and rubbish in steady drizzle, happy as Larry. Why? Imagine wiping the raindrops off your scope eyepiece, lowering your head, and focusing: there, in among the throngs of gulls on an unpleasant January afternoon, was Britain’s first Slaty-backed Gull, settled, preening, and giving excellent views.

That was actually the last time I saw the bird, only about 24 hours after I'd found it. Others got lucky in the weeks that followed, but I only ever did manage to see it on those first two days.

A long time passed before I finally submitted the record, having done all the research I felt necessary for such a bird. That lengthy submission and a series of photos are still doing the rounds with the Rarities Committee, but those interested in this Pacific vagrant might like to know that I’ve just submitted a supplementary note on the record.

In brief, it relates to new evidence provided by Peter Adriaens about the variability in the darkness of this species’ upperparts – the main talking point of the London bird, with some believing it was not dark enough. Peter visited Japan earlier in the year and spent two weeks watching and photographing gulls at Chosi. Images from his trip, now uploaded online and with informative captions, show that, in his words, “variation in mantle colour does not necessarily reflect hybridisation, but is also simply age-related”. He also addresses the question of hybrids, believing they should show more than one anomalous trait. The image galleries are viewable here:

Tuesday, 11 September 2012

Juvenile Baillon's Crake at Rainham Marshes RSPB today. Wandering vagrant or British bird, born and bred?

With news breaking late in the season that up to nine singing Baillon's Crakes had been found in Britain this summer (see Birdwatch 243: 60-61), every patchworker worth their salt has been checking suitable habitat for this species, which has hitherto had the cachet of being a true 'mega'. In the Birdwatch office, such is its desirability that we even fantasised about finding one at Rainham Marshes RSPB, my own patch and a regular stomping ground for two more of the team.

Well, in the end the honours fell to a former rather than current Birdwatch team member. Marianne Taylor was at Rainham last Friday afternoon (7th) when she located Porzana pusilla; her account of discovering London's bird of the year will be in the next issue of her old magazine. Only a handful of regulars saw it before dark, and then news was released widely that evening. Large numbers of birders were expected at dawn, so as a Volunteer Bird Recorder at the reserve I was on site by 05:30 and took up position in the Butts Hide with the first early-rising visitors and fellow VBR Ruth Barnes.

The nervous anticipation of whether or not a mega-rarity has overnighted is not a pleasant sensation, so we began searching for it even though the pre-dawn murk hampered the task. But scanning along the edge of the rushes in the gloom, I picked up what looked like a pale motionless 'blob' just off the ground. Getting the scope on it and zooming in, the blob lifted its head and looked around - Baillon's! I called it out and some of the replies were almost disbelieving, but there it was, now moving left through the edge of the rushes.

The Tower Butts Hide at Rainham has been almost permanently occupied during opening hours since Saturday morning, with visitors from far and wide attempting to see the bird.

We all watched as the light slowly brightened, and I guess the bird was in full view for perhaps 35 minutes or so before moving right into a hidden channel and becoming more elusive. Birders were still arriving constantly and we managed to get many of them straight onto it (with the notable exception of Hawky, who missed it by minutes and spent another 15 or so hours on three visits over the weekend before finally connecting). Thereafter, the crake went AWOL, not to be seen again that day nor the following morning until just before 10:00. I volunteered on Sunday too and again on Tuesday, when I took these record shots when the bird showed briefly mid-morning (in contrast to the Aquatic Warbler reported by two observers the previous day in the same location).

A record shot of the bird on the move as it breaks cover and heads into the water ...

... and then swims in the open for a short distance before sheltering once more among the rushes.

This was a tick that even the most veteran of London listers needed, given that the previous two records in the capital date from the 19th century (1871 and 1894). While I was there many of them succeeded in nailing it, albeit with some effort. Less twitch and more vigil it may have been, but ultimately this cracking crake was well worth the wait.

The same bird as above, holding its ground against an aggressive Herring Gull. Caspians are happy to slug it out with other large gulls and can often be dominant in a feeding frenzy, pecking rivals and chasing them away.

A quick update on my latest visit to the Thames for gulls. Highlights included the very high total count of 145 Yellow-legged Gulls at Rainham from the RSPB visitor centre west to the stone barges (72 of them at the western end during my four hours on site), the third-winter atlantis-typeYellow-legged Gull (but not necessarily an atlantis proper), another oddly marked apparent juvenile/first-winter Yellow-legged with a pale bill and bizarre two-tone head pattern, and up to five Caspian Gulls, including at least one full juvenile and three first-summers. A Herring-type showing some interesting characters might be the subject of a separate post in due course.

Up next: that so-called atlantis third-winter and another Yellow-legged oddity - please click the link.

Saturday, 1 September 2012

Date: Sunday 2 September 2012Time: 08:00Meeting place: The Grove car park, Alexandra Park, London N10Transport: car parking usually available at the meeting point or nearby in Dukes Avenue N10. Public transport: the W3 bus between Wood Green (Piccadilly Line) and Finsbury Park (Piccadilly and Victoria Lines) stops by the Grove. Overground services call at Alexandra Palace station (25-minute walk)What to bring: binoculars, clothing and footwear appropriate to the weather, refreshments as required

Alexandra Park Ornithological Group is running a free guided walk this Sunday. Gareth Richards and I will be leading the walk, and our route through the park will include the area known as the Cricket Scrub, where Gerry Rawcliffe, assisted by Bob Watts, will be holding a ringing demonstration. We should see a wide range of common woodland and parkland birds, hopefully including woodpeckers, and depending on weather conditions migrants may be in evidence - sightings in the last two days include such interesting species as Yellow Wagtail and Common Redstart. The walk will last two-three hours, depending on bird activity. Children are welcome, but no dogs please.